Book contents
- Frontmatter
- Contents
- List of contributors
- Foreword
- Editors' preface
- Preface
- Acknowledgments
- Part I An overview of the contributions of John Archibald Wheeler
- Part II An historian's tribute to John Archibald Wheeler and scientific speculation through the ages
- Part III Quantum reality: theory
- 3 Why is nature described by quantum theory?
- 4 Thought-experiments in honor of John Archibald Wheeler
- 5 It from qubit
- 6 The wave function: it or bit?
- 7 Quantum Darwinism and envariance
- 8 Using qubits to learn about “it”
- 9 Quantum gravity as an ordinary gauge theory
- 10 The Everett interpretation of quantum mechanics
- Part IV Quantum reality: experiment
- Part V Big questions in cosmology
- Part VI Emergence, life, and related topics
- Appendix A Science and Ultimate Reality Program Committees
- Appendix B Young Researchers Competition in honor of John Archibald Wheeler for physics graduate students, postdoctoral fellows, and young faculty
- Index
5 - It from qubit
from Part III - Quantum reality: theory
Published online by Cambridge University Press: 29 March 2011
- Frontmatter
- Contents
- List of contributors
- Foreword
- Editors' preface
- Preface
- Acknowledgments
- Part I An overview of the contributions of John Archibald Wheeler
- Part II An historian's tribute to John Archibald Wheeler and scientific speculation through the ages
- Part III Quantum reality: theory
- 3 Why is nature described by quantum theory?
- 4 Thought-experiments in honor of John Archibald Wheeler
- 5 It from qubit
- 6 The wave function: it or bit?
- 7 Quantum Darwinism and envariance
- 8 Using qubits to learn about “it”
- 9 Quantum gravity as an ordinary gauge theory
- 10 The Everett interpretation of quantum mechanics
- Part IV Quantum reality: experiment
- Part V Big questions in cosmology
- Part VI Emergence, life, and related topics
- Appendix A Science and Ultimate Reality Program Committees
- Appendix B Young Researchers Competition in honor of John Archibald Wheeler for physics graduate students, postdoctoral fellows, and young faculty
- Index
Summary
Introduction
Of John Wheeler's “Really Big Questions,” the one on which the most progress has been made is “It from bit?” – does information play a significant role at the foundations of physics? It is perhaps less ambitious than some of the other questions, such as “How come existence?”, because it does not necessarily require a metaphysical answer. And unlike, say, “Why the quantum?”, it does not require the discovery of new laws of nature: there was room for hope that it might be answered through a better understanding of the laws as we currently know them, particularly those of quantum physics. And this is what has happened: the better understanding is the quantum theory of information and computation.
How might our conception of the quantum physical world have been different if “It from bit” had been a motivation from the outset? No one knows how to derive it (the nature of the physical world) from bit (the idea that information plays a significant role at the foundations of physics), and I shall argue that this will never be possible. But we can do the next best thing: we can start from the qubit.
Qubits
To a classical information theorist, a bit is an abstraction: a certain amount of information. To a programmer, a bit is a Boolean variable. To an engineer, a bit is a “flip-flop” – a piece of hardware that is stable in either of two physical states.
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- Information
- Science and Ultimate RealityQuantum Theory, Cosmology, and Complexity, pp. 90 - 102Publisher: Cambridge University PressPrint publication year: 2004
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